An end mill is mainly used for a side cutting, a groove cutting, and similar cutting in mold machining. However, in parts machining on difficult-to-machine material (work material) such as stainless steel, a service life of a tool tends to be decreased due to chip easily welded on a tip of a cutting edge. In this respect, the end mill is requested to have a function to improve machining efficiency to reduce a machining time for prolonging the service life of the tool.
The chip welded on the tip of the cutting edge is caused by the chip immediately after a cutting by the cutting edge not to be discharged from a rake face immediately. Then, it is considered that sufficiently ensuring a dischargeability of the chip from a cutting edge rake face avoids the chip from being welded.
As means to improve the chip dischargeability from the cutting edge rake face, there has been a method that a plurality of gash faces are formed to constitute gashes continuous with the rake faces and chip discharge grooves, so as to guide the chip on the rake faces to the chip discharge grooves (see Patent Documents 1 to 5).
Patent Documents 1 to 5 each include the end cutting edge rake faces and the gashes constituted of the plurality of the gash faces opposing the end cutting edge rake faces on a front side in a rotation direction, and have the plurality of the gash faces opposing the end cutting edge rake faces inclined from a center side in a radial direction to an outer peripheral side by an angle close to a rotation axis of a tool body, so as to guide the chip from the gashes to the chip discharge grooves.